Over 60% of advanced cancer patients suffer weight loss. This weight loss predicts early death, is associated with lean tissue erosion and marked debility, and detracts from quality of life. To date, no treatment has been shown to reverse weight loss and its devastating consequences in patients with refractory, advanced cancer. Creatine offers a novel approach. Used by athletes and "body builders," creatine has been studied in over 50 clinical trials and appears to augment weight, musculature, and strength with an acceptable short-term toxicity profile. To our knowledge, no study has examined creatine in cancer patients. Building upon a decade's worth of clinical investigation into weight loss issues in cancer patients, we hypothesize that creatine may benefit cancer patients as well. We therefore propose a trial with creatine with the following specific aims: 1. To explore if creatine stabilizes weight in weight-losing cancer patients. We will compare the percentage of patients with continued weight loss (greater than or equal too 5% of baseline weight) over 6 weeks in a cohort of 25 creatine-treated and 25 placebo-treated patients, all of whom are receiving the same chemotherapy regimen. We will also compare time-to-weight loss between the two treatment arms. 2. To explore whether creatine augments lean tissue and improves strength in weight-losing cancer patients. We will measure lean tissue and handgrip strength at baseline and at 6 weeks in this same cohort of 50 patients. We will make direct comparisons of these 2 parameters between treatment arms. 3. To explore whether creatine's toxicity and quality of life profile is acceptable. We will obtain longitudinal toxicity and quality of life data on this same cohort of 50 patients and will make direct comparisons between treatment arms on toxicity incidence and severity and on maximal quality of life scores